1. Field of the Invention
The present invention relates to single-strike die and a method for using the die to produce a medical suturing device. More particularly, the present invention relates to a single-strike die and a method for using the die to attach a surgical suture to a surgical needle.
2. Description of the Prior Art
The medical procedure of suturing by hand a surgical or other wound in tissue or organs involves the use of a surgical needle with a surgical suture attached thereto. For simplicity, reference will be made hereafter only to suturing of tissue.
Typically, the needle punctures the tissue from the outside on one side of the wound, traverses across the wound and then punctures the tissue from the inside on the other side of the wound, pulling the suture through these punctured openings. The suture is then tied-off to form a single suture, or stitch, and to close the wound between the punctured openings. This procedure is repeated along the length of the wound. The needle is usually curved to make it easier to push through both sides of the tissue and includes a sharpened tip at its lead or distal end and a hollow barrel at its trailing or proximal end, which is hollow by virtue of being formed with a blind axial hole. The suture is axially inserted into the hollow end and secured in the barrel. It is important to tightly secure the suture within the barrel so it does not loosen and become separated from the needle during the hand-suturing procedure.
The art of attaching a surgical suture to the barrel of a surgical needle has been practiced for many years. One conventional method that has been practiced uses two opposing dies that are machined to have end profiles which complement the shape and diameter of the barrel of the needle. U.S. Pat. Nos. 4,306,443; 4,722,384; and 4,799,311 relate to crimping apparatus of this type. With the suture inserted into the hollow barrel of the needle, one die moves relative to the other to crimp the barrel at one location about its periphery. After the first crimping operation, the needle is manually rotated and a second and sometimes a third crimping operation is performed to securely crimp the suture within the barrel of the needle. However, several drawbacks associated with this method, such as the time consumed in performing several crimping operations and the imprecision of choosing the locations on the barrel to be crimped, make this an unsatisfactory procedure.
Another conventional method for attaching a surgical suture to the hollow barrel of a surgical needle involves the use of a single-strike die. The die is so named because it crimps the barrel of the needle in a plurality of locations in a single crimping procedure. Canadian Patent No. 1,022,734 shows such a single-strike die for securing a suture to a surgical needle. Two dies are used to perform the crimping, or swaging, procedure. In one example, each die is machined to have a die profile with two flat faces formed at a 90.degree. angle to one another thereby to define a V-shaped notch. As the dies are compressed about the suture-containing needle barrel, the needle is crimped at four radial locations about the barrel. Another example shows one die with a flat face and a second die with a V-shaped opening that together crimp the suture-containing needle at three locations about the barrel. However, the multi-faceted profiles of these dies are expensive to machine. Moreover, these die profiles are machined to fit specific barrel diameters. Therefore, the dies must be changed if needles with barrels of a different diameter are to be crimped.
Conventional methods for securing surgical sutures to surgical needles also suffer from requiring too much manual input from the machine operators. Throughout a working day, repeated turning of the needle between crimps, or manually regulating the crimping pressure of the machines, which often use pneumatic drive systems or electrically powered cam-actuated drive systems, can reduce the speed and efficiency of producing suture-containing needles. Still further, requiring the operator to determine the locations on the barrel to be crimped or the amount of pressure to be applied to the needle leads to inconsistent quality and inferior suture-containing needles and increases the failure or rejection rate. For example, if the barrel of the needle is not crimped at enough locations or the locations are not properly spaced around the barrel, the suture can slip out of the barrel during the hand-suturing procedure. In addition, if the operator regulates the conventional dies to apply too much pressure to the barrel it may crack and in such case the needle will have to be discarded.
Accordingly, further improvements and advances in single-strike dies, methods of using single-strike dies to provide medical suturing devices, and medical suturing devices comprising surgical needles with securely attached surgical sutures are needed.